This is difficult for Canadians, who have long thought that they are more liberal, that they’re more tolerant of visible minorities, that America is a melting pot of conformity. No longer.

Indeed, so great is Barack Obama’s appeal that he could become a third force in our politics.

He’s more popular than Harper here, and that gives him credibility.

The president’s influence, should he use it, may be greatest in climate change; Obama is expected to urge Canada to adopt higher continental standards on carbon emissions. This is a problem for Harper, who has supported the tarsands in Alberta, a huge source of pollution.

Then there is Afghanistan, where the Americans are increasing their military commitment.

They will probably ask us to stay longer than 2011, when our troops are to leave.

As the president prepares to come to Ottawa, Harper will learn there is another leader of the opposition. His name is Barack Obama.